Mariadb mysql_upgrade执行失败求助：从10.1.36升级至10.2.30后报错

Hey there, let's break down why your mysql_upgrade is failing at step 4. Based on common issues with this specific upgrade path, here are the most probable causes and actionable fixes:

• Corrupted or inconsistent system tables
  MariaDB 10.2 introduced changes to core system tables (like adjustments to the mysql.user table structure). If your pre-upgrade system tables had any corruption or inconsistencies, the upgrade process can get stuck at step 4.
  Fix: First, repair all databases and tables with the mysqlcheck tool before re-running the upgrade. Execute this as the root user:

  mysqlcheck --all-databases --repair --extended -u root -p
  

  Enter your root password when prompted, then try running mysql_upgrade -u root -p again.

• Insufficient privileges for the upgrade user
  If you're not running mysql_upgrade with a user that has full access to system databases, the process can fail when trying to modify critical tables.
  Fix: Always run the upgrade command with the root user (or a user with ALL PRIVILEGES on the mysql database and SUPER privilege). Use this explicit command:

  mysql_upgrade -u root -p
  

• Stale processes or lock files blocking the upgrade
  Interrupted processes from the initial upgrade can leave behind locks or stray mysqld threads that interfere with mysql_upgrade.
  Fix:

  1. Stop the MariaDB service entirely:

     systemctl stop mariadb
     

     (Use service mariadb stop if you're on an older Linux distro without systemd)
  2. Check for remaining mysqld processes:

     ps aux | grep mysqld
     

     Kill any leftover processes with kill <process_id> if needed.
  3. Restart the MariaDB service:

     systemctl start mariadb
     

  4. Re-run the upgrade command.

• Conflicting settings in your my.cnf configuration
  MariaDB 10.2 has new default configuration values that might clash with your old my.cnf file (e.g., changes to sql_mode or system table parameters).
  Fix: Temporarily rename your existing config file to avoid conflicts:

  mv /etc/my.cnf /etc/my.cnf.bak
  

  Start MariaDB with default settings, run mysql_upgrade -u root -p, then restore your config file and adjust any settings that don't align with 10.2's requirements.

If your screenshot shows a specific error message (like a mention of a particular system table), you can narrow down the fix by repairing that table specifically with mysqlcheck --repair mysql <table_name>.

内容的提问来源于stack exchange，提问作者Jakub Barták